In simple terms, this means all power could come from sources like wind, solar and hydro without reliance on fossil fuels. This has been the position of environmental groups and renewable energy companies. But not utilities, which typically argue that the grid still requires fossil electricity for stability, because renewables come and go.

“I am speaking with confidence now. We have a solution now to adjust the intermittency of solar and wind energy that is no longer a technology challenge. Now it is an economic decision,” said Patrick Lee, Sempra Energy vice president for major project controls. “So installing a base load power plant is no longer your only option. You can now look at solar, wind and storage as alternatives, and still be able to manage the reliability of the grid. So that is the takeaway I would like you to have.”

Lee said that as a trained engineer, even three years ago he would not have believed this was possible.

“But today my answer is: The technology has been resolved. How fast do you want to get to 100 percent? That can be done today,” he said.

In those three years, not only have wind, solar and battery prices plunged. The software to control storage and the grid has also advanced.

Suddenly, there is software that can make grid adjustments and bring battery power online much, much faster. “We now have the ability to control the grid twenty times faster than you can blink your eye,” Lee said.

To commercialize the new control software, Sempra has spun off a company called Pxise Energy Solutions, LLC. It has licensed several patents developed with the company OSIsoft. Pxise has three more patents in the works. Lee is president of Pxise.

New abilities like this help point the way to future profit for utilities like Sempra facing financial challenges from many energy trends. But they also raise questions about the necessity of controversial new fossil fuel plants that these companies still want to build, such as the one near the beach in Carlsbad. Until recently, Sempra and that plant’s builder, NRG Energy, had countered, saying batteries were just not there yet.